Electric discharge lamp



Dec. 17, 1935. c H, BRASELTQN' 2,025,023

ELECTRIC DISCHARGE LAMP Filed Aug. 25, 1952 INVENTOR Patented Dec. 17, 1935 UNITED STATES ELECTRIC DISCHARGE LAIHP Chester H. Braselton, New York, N. Y., assignor to Sirian Lamp Company, Newark, N. J., a corporation of Delaware Application August 25, 1932, Serial No. 630,381

2 Claims.

This invention relates to electric lamps of the discharge type and has for its principal object the provision of a lamp with an exceptionally long life.

Another object of the invention is to provide a lamp in which the electrodes have access to more gas than is required in their immediate vicinity to produce the desired discharge.

Another object of the invention is to provide a 10 discharge lamp in which the discharge electrodes are surrounded by an interior envelope which communicates with the main envelope.

'Other objects of the invention and objects relating particularly to the method of constructing 15 and assembling the various parts will be apparent as the description of the invention proceeds.

The invention is illustrated in the accompanying drawing in which:

Fig. 1 is a perspective view, partly in section, of 20 a lamp embodying the invention; and

Fig. 2 is a sectional plan view taken on the line 2-2'of Fig. 1.

In discharge lamps where a pair of electrodes are mounted spaced apart and surrounded by 25 an ionizable gas, such as neon, the resultant discharge is dependent not only upon the size and shape of the electrodes, the spacing thereof, the kind of gas used, and the voltage applied to the electrodes, but also to the amount of space within 30 the envelope and surrounding the electrodes. It has been found that in operating discharge lamps having a certain pressure of gas therein that continued use of the lamp apparently causes an absorption of the gas by the electrodes with the re- 35 sult that the gas pressure becomes less and less, afiecting the character of the discharge, until finally it becomes so low that no discharge at all appears. The present invention overcomes this difiiculty by greatly increasing the amount of 40 available gas while maintaining the space conditions around the electrodes. Thus the percentage of occlusion of gas per unit of operating time is greatly diminished and the lamp lasts materially longer.

45 To this end the construction shown in the may be applied to the press before the press is sealed into the larger envelope and is of sufilcient size to give the desired discharge between the plate. In the top of the envelope I4 is a hole 15 large enough to permit the free flow of gas from 5 the inner envelope into the outer and vice versa.

With the elements constructed as indicated in the drawing the lamp may be connected in the usual manner in an exhaust pump and an oven placed over it to raise the temperature of the parts so as to remove occluded gases. After the envelope has been completely exhausted as is evidenced by the lack of fluorescence when high tension current is directed against the walls of the envelope the vacuum pump may be turned off and a suitable amount of an ionizable gas admitted, such as argon, neon,.helium, krypton, xenon, or mixtures of such gases, with the addition, if desired, of a metal vapor, such as one or more of the vapors of mercury, caesium, or rubidium. The pressure of the gas may be varied depending somewhat on the discharge desired and the voltage with which the lamp is intended to be used, but preferably it should not exceed 5 mm. of mercury.

When such a lamp is connected to an electrical circuit with the proper voltage a discharge appears between the plates concentrating on the negative electrode but ionizing to some extent all the gas which is in the inner envelope. The gas in the outer envelope, however, is so completely separated from the area of the discharge that it does not become ionized but there is a free flow of gas into' and out of the inner envelope from the outer one, the result being that the electrodes have access to all of the gas in the outer envelope. If the electrodes absorb any of the gas the percentage so absorbed will be very much lower than if the inner bulb were the only envelope surrounding the electrodes, but at the same time the dis 40 charge is governed more or less by the size and shape of the inner envelope. As illustrated in Fig. 1 of the drawing, the lamp is positioned in an upright position and the opening I5 is accordingly directed above the electrodes l2 so that heated gases rising from the electrodes pass readily through the opening into the outer space within the envelope III. The lamp, however, is not necessarily restricted to use in an upright position as the equalizing function of the vent I5 is effective in all positions of the lamp. 7

While I have shown a discharge lamp similar to the glow type neon lamp it will be understood that any type of discharge lamp may have its life increased by the use of the invention and I do not, therefore, desire to limit myself to what has been shown and described except as such limitations occur in the appended claims.

What I desire to claim and secure by Letters Patent is:

1. In a discharge lamp an envelope, a plurality of electrodes within said envelope, inert gas surrounding said electrodes and having a pressure of less than 5 mm. of mercury, and an inner envelope, having a relatively small opening at its upper end, completely surrounding said electrodes.

2. In a discharge lamp an envelope, a plurality of electrodes within said envelope and mounted upon said press, a quantity of neon gas within said envelope at a pressure of less than 5 mm. of mercury, and an inner envelope surrounding said electrodes and mounted upon said press, said in-' ner envelope having an opening in the upper end thereof of a size suihcient to limit ionization to gases while permitting free movement of gases to points without.

CHESTER H. BRASELTON. 

